<style type="text/css">
    .red
    {
        background-color:red;
    }
</style>

<script language="javascript" type="text/javascript">
        window.onload=function()
        {
            var trList = document.getElementById("repeater");
            for(var i=0;i<trList.rows.length;i++)
            {
                trList.rows[i].onclick=SetColor;
            }
        }
        function SetColor()
        {
            var trList = document.getElementById("repeater");
            for(var i=0;i<trList.rows.length;i++)
            {
                trList.rows[i].className="";
            }
            this.className="red";
        }
    </script>